The Collaborative International Dictionary of English v.0.48:

Phaethon \Pha"["e]*thon\ (f[=a]"[-e]*th[o^]n), prop. n. [L.,
   Pha["e]thon (in sense 1), fr. Gr. Fae`qwn, fr. fae`qein,
   fa`ein, to shine. See Phantom.]
   1. (Class. Myth.) The son of Helios (Ph[oe]bus), that is, the
      son of light, or of the sun. He is fabled to have obtained
      permission to drive the chariot of the sun, in doing which
      his want of skill would have set the world on fire, had he
      not been struck with a thunderbolt by Jupiter, and hurled
      headlong into the river Po.
      [1913 Webster]

   2. (Zool.) A genus of oceanic birds including the tropic
      birds.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Phaethon
    n 1: (Greek mythology) son of Helios; killed when trying to
         drive his father's chariot and came too close to earth
    2: type genus of the Phaethontidae [syn: Phaethon, genus
       Phaethon]

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "Phaethon":
   Agdistis, Amen-Ra, Amor, Aphrodite, Apollo, Apollon, Ares, Artemis,
   Ate, Athena, Bacchus, Ceres, Cora, Cronus, Cupid, Cybele, Demeter,
   Despoina, Diana, Dionysus, Dis, Eros, Gaea, Gaia, Ge, Great Mother,
   Hades, Helios, Hephaestus, Hera, Here, Hermes, Hestia, Hymen,
   Hyperion, Jove, Juno, Jupiter, Jupiter Fidius, Jupiter Fulgur,
   Jupiter Optimus Maximus, Jupiter Pluvius, Jupiter Tonans, Kore,
   Kronos, Magna Mater, Mars, Mercury, Minerva, Mithras, Momus,
   Neptune, Nike, Olympians, Olympic gods, Ops, Orcus, Persephassa,
   Persephone, Phoebus, Phoebus Apollo, Pluto, Poseidon, Proserpina,
   Proserpine, Ra, Rhea, Saturn, Savitar, Shamash, Sol, Surya, Tellus,
   Titan, Venus, Vesta, Vulcan, Zeus